Welcome to our resource for MG Car Information.



MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGB Technical - Clutch Slave Cylinder

Tried to drive the car out of the garage this morning, clutch biting point right at the end of pedal travel. Checked reservoir, no fluid. Checked slave cylinder, wet with fluid. So that looks like a leak then!

Haynes manual says to undo pipe, undo two bolts and the job's done. Is it really as simple as that? Seems pretty hard to get at when I had a poke around...


I did it but about 5 years ago-so my memory may be hazy! Suggest replace the flexible pipe and I wouldn't bother trying to rebuild the slave cylinder-it seldom works IMO-replace it! I think you should check for wear-linkage holes have a habit of going oval! Then comes the problem of refilling the system! I managed to fill it thru the bleed nipple upwards so it expelled the air upwards. An ezibleed might do it but I think I used an old jam jar, fitted a bicycle wheel valve thru the lid, and a second tube thru a second hole (sealed with silicone) down into the fluid, with the other end on the bleed nipple(open). Bike pump on the valve and liquid is forced up the pipe into the slave up the pipe into the master. Shut off bleed nipple if you need to refill jam jar or it will all piddle out.....Second person keeps a check to prevent overflow as fluid is corrosive... HTH Michael
Michael Beswick

I'd consider a repair kit before replacing the slave, for the following reason: Unless the thread for the hose the same position in both cylinders when you tighten the hose the slave will only bolt back up to the bell housing by twisting the hose, which should be avoided. If it screws in a bit too far you can add a washer, but if it doesn't screw in far enough you are a bit stuck. BT, DT. I wanted to change the flex hose as well but simply could not shift either of the nuts at the other end of the hose as access is so poor so couldn't even twist the metal pipe a bit so the hose lined up. I was lucky and an extra washer did the trick. If you can get the hose off then yes I'd replace both, although I found the slave surprisingly expensive, much the same as for a master. If fitting a new one make sure you end up with the bleed nipple in the top space pointing across the car and the hose in the front hole that faces forwards, the nipple usally ships in the wrong position.

To change the seal simply undo the bolts and let the slave hang down on the hose while you change the parts, should only take moments.

Bleeding is done easiest by simply connecting a hose between the slave nipple and the left caliper nipple, opening both, then using the brake pedal gently and slowly to reverse fill/bleed the clutch from the brake system. Drain some fluid out of the clutch first (unless already low from the leak ho ho) to avoid overflowing onto paint. There should be no chance of reducing the brake level too much, but it is something to watch out for if you have to do it several times for any reason.
Paul Hunt

Thanks Michael and Paul. I had the engine out about 10 years ago (time flies) and doubt that I would have put the whole lot back together without a new slave cylinder (I changed everything else!) so seals may be the way to go... On the other hand, I replaced the master cylinder a couple of years ago and renewed the pipes then, so they should come apart okay.

How easy is it to actually get at the slave cylinder to undo the bolts? If it's dead easy then I'll try some seals on the basis that I haven't lost much if that doesn't work. If it's a pig then I'll put a new slave cylinder in there; maybe overkill...


Getting to the slave bolts is easy. They are out in the open. I would opt for the kit as it is inexpensive. Check the interior of the slave for pitting and if it is clean the kit will solve your problem. If badly pitted then it is time to replace. RAY

I replaced mine at the end of last year, I opted to replace the slave cylinder rather than rebuild the existing one. The job was quite easy actually, went smoothly with no problems. I attached the hose to the slave cylinder 1st then to the pipe going to the clutch master and then lastely connected the slave cylinder to the bell housing. Everything went well with no twists in the hose. Paul's comment about the bleed nipple is a good one as they always ship the new slave with the nipple in the wrong spot so be aware of that, otherwise it's a pretty straight forward job.
JCH Hibbard

I would replace the whole lot including flexi, Paul, I have just bought a new set ready for my rebuild from Midland classics and it was only 26 inc the flexi. (no connection with that company at all just local to it)
N Hatton

Midland Classics do indeed currently have them at about half price, I don't know how. No help to me though as I needed one there and then and Leacy is much nearer than Ombersley.

When I had to replace the master on the V8 I also opted to replace the flex and slave as a matter of course, but the chassis end of the flex is much more accessible on those than the 4-cylinder. The annoying thing is that we had just had the 4-cylinder engine out for a clutch change, giving us ideal access if we had decided to change the slave and hose anyway instead of only afterwards when it leaked!
Paul Hunt

Replacing the hose in situ is a real pig. The outer nut is usually siezed and can be almost impossible to reach with ordinary tools. Penetrating oil and a crow foot spanner are a neccessity. RAY


Don't forget the anti-seize...

This thread was discussed between 28/02/2009 and 03/03/2009

MG MGB Technical index

This thread is from the archive. The Live MG MGB Technical BBS is active now.